The knee is generally regarded as being the most inherently unstable of the joints of the human body, due in part to the complex of inter-related types of motions to which the several knee elements are subjected during the normal acts of walking, running, climbing and the like, which include relative sliding and rolling movements as well as rotation about both horizontal and vertical axes. In the past various mechanical approaches have been proposed in the attempt to approximate, through an artifical joint, the natural action of the human knee. Advanced conditions of disease or serious traumatic injury of the knee joint complicate surgical repair and efforts to simulate the natural knee motion through use of a prosthesis.
Under circumstances wherein the condyles of the knee are beyond acceptable repair by means of surgical replacement of only the articular surfaces thereof, it has been common practice to attempt joint reconstruction by means of one or the other of three general types of prothesis, which are: a first type which relies on a mechanical hinge, a second which is characterized by a ball-and-socket arrangement, and a third in which the femoral and tibial components are unconnected. Each of these has typical advantages and disadvantages of implantation and of therapeutic value.
The general objects of the present invention are to provide a new and improved joint prosthesis, generally of the hinged type, for the replacement of a seriously impaired human knee, which combines the mechanical strength of a pintle hinge with rotational freedom, which situates the horizontal pivot in a natural location posteriorly offset from the location of tibial-femoral contact, which affords ease of alignment and assembly during its surgical installation, and which incorporates means for absorbing any shock of engagement between the femoral and tibial components.